Runout 3D line or cylinder

[[po...]]

Which is better to use for runout datum a cylinder or a 3D line recalled from two circles measured in the cylinder. The a 3D line seems to give lower numbers than a cylinder. Is due to the cylinder axis is extend out forever and a 3D line is only the length from circle to circle?  

 

[[Ma...]]

Datum A is evaluated as outer tangential.

[[RP...]]

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So what you're saying is, per print, Datum -A- should be a cylinder with OT eval instead, not LSQ eval for the runout callout?  I assumed short cylinders would be better evaluated as 3d lines.

[[Ma...]]

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I'm just saying how is this cylinder treated as a datum in any callout. This datum looks like 1:1 ratio

[[Da...]]

ASME or ISO?

[[Ma...]]

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 in both

[[Lu...]]

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Yes in ISO you have the ISO 5459 that establish in other stuff DATUM and the evaluation for datum is like ASME outer tangengial. not LSQ.